Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, United States.
Virology. 2013 Feb 5;436(1):118-26. doi: 10.1016/j.virol.2012.10.039. Epub 2012 Nov 29.
We investigated whether soluble EBV gH/gL (sgH/gL) functions in fusion and made a series of truncations of gH/gL domains based on the gH/gL crystal structure. We found sgH/gL failed to mediate cell-cell fusion both when co-expressed with the other entry glycoproteins and when added exogenously to fusion assays. Interestingly, sgH/gL inhibited cell-cell fusion in a dose dependent manner when co-expressed. sgH/gL from HSV was unable to inhibit EBV fusion, suggesting the inhibition was specific to EBV gH/gL. sgH/gL stably binds gp42, but not gB nor gH/gL. The domain mutants, DI/gL, DI-II/gL and DI-II-III/gL were unable to bind gp42. Instead, DI-II/gL, DI-II-III/gL and sgH/gL but not DI/gL decreased the expression of gp42, resulting in decreased overall fusion. Overall, our results suggest that domain IV may be required for proper folding and the transmembrane domain and cytoplasmic tail of EBV gH/gL are required for the most efficient fusion.
我们研究了可溶性 EBV gH/gL(sgH/gL)是否在融合中发挥作用,并根据 gH/gL 晶体结构对 gH/gL 结构域进行了一系列截断。我们发现,sgH/gL 与其他进入糖蛋白共表达或在融合实验中添加时均不能介导细胞-细胞融合。有趣的是,sgH/gL 在共表达时以剂量依赖的方式抑制细胞-细胞融合。HSV 的 sgH/gL 不能抑制 EBV 融合,表明抑制作用是 EBV gH/gL 特异性的。sgH/gL 稳定结合 gp42,但不结合 gB 或 gH/gL。结构域突变体 DI/gL、DI-II/gL 和 DI-II-III/gL 不能结合 gp42。相反,DI-II/gL、DI-II-III/gL 和 sgH/gL 但不是 DI/gL 降低了 gp42 的表达,导致整体融合减少。总的来说,我们的结果表明,结构域 IV 可能是正确折叠所必需的,而 EBV gH/gL 的跨膜结构域和胞质尾可能是最有效的融合所必需的。